Read UTF-8 files correctly with PowerShell

Question

Following situation:

• A PowerShell script creates a file with UTF-8 encoding
• The user may or may not edit the file, possibly losing the BOM, but should

Answer 1

If the file is supposed to be UTF8 why don't you try to read it decoding UTF8 :

Get-Content -Path test.txt -Encoding UTF8

Answer 2

Really JPBlanc is right. If you want it read as UTF8 then specify that when the file is read.

On a side note, you're losing formatting in here with the [String]+[String] stuff. Not to mention your regex match doesn't work. Check out the regex search changes, and the changes made to the $newMsgs, and the way I'm outputting your data to the file.

# Read data if exists
$data = ""
$startRev = 1;
if (Test-Path test.txt)
{
    $data = Get-Content -Path test.txt #-Encoding UTF8
    if($data -match "\br([0-9]+)\b"){
        $startRev = [int]([regex]::Match($data,"\br([0-9]+)\b")).groups[1].value + 1
    }
}
Write-Host Next revision is $startRev

# Define example data to add
$startRev = $startRev + 10
$newMsgs = @"
2014-04-01 - r$startRev`r`n`r`n
    Line 1`r`n
    Line 2`r`n`r`n
"@

# Write new data back
$newmsgs,$data | Out-File test.txt -Encoding UTF8

Answer 3

Get-Content doesn't seem to handle UTF-files without BOM at all (if you omit the Encoding-flag). System.IO.File.ReadLines seems to be an alternative, examples:

PS C:\temp\powershellutf8> $a = Get-Content .\utf8wobom.txt
PS C:\temp\powershellutf8> $b = Get-Content .\utf8wbom.txt
PS C:\temp\powershellutf8> $a2 = Get-Content .\utf8wbom.txt -Encoding UTF8
PS C:\temp\powershellutf8> $a
ABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ  <== This doesnt seem to be right at all
PS C:\temp\powershellutf8> $b
ABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ
PS C:\temp\powershellutf8> $a2
ABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ
PS C:\temp\powershellutf8>
PS C:\temp\powershellutf8> $c = [IO.File]::ReadLines('.\utf8wbom.txt');
PS C:\temp\powershellutf8> $c
ABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ
PS C:\temp\powershellutf8> $d = [IO.File]::ReadLines('.\utf8wobom.txt');
PS C:\temp\powershellutf8> $d
ABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ <== Works!